1. Field of the Invention
The present invention has to do with a barrier layer which inhibits the migration of underlying organic stain into the decorative portion of floor covering and wall covering materials. More particularly, the invention relates to a barrier layer comprised of a plastisol and sodium silicate which is incorporated into a floor or wall covering to inhibit the migration of organic materials from the surface underlying the floor or wall covering into the decorative portion thereof.
2. Description of Related Art
Floor covering and wall covering materials frequently are applied over surfaces which have been coated or marked with organic substances such as sealants, wood stains, ink from marking pens, asphalt, oil based paints and the like. These organic substances can migrate or diffuse into the floor or wall covering and cause staining of the decorative portion thereof, which destroys the decorative appearance.
Organic substances can cause staining of a variety of floor and wall coverings such as carpeting, sheet vinyl flooring, and cloth or vinyl wall coverings. Sheet vinyl flooring and wall covering products are particularly vulnerable because they contain plasticizers which are compatible with organic substances. The stains thereby diffuse into the floor or wall covering by means of the plasticizer as a vehicle. The higher the plasticizer content, normally, the faster the stain diffuses. According to the preferred embodiment of the present invention, a barrier which inhibits such migration is incorporated in the sheet material as a layer which may be adhered as the back or underside of the sheet material, or incorporated between the back and the decorative portion of the sheet material.
Sodium silicates, called water glass when they are dissolved in water, have been employed in coatings and adhesives. U.S. Pat. No. 1,365,715, for example, discloses the use of sodium silicate as a replacement for a part of the glue used in sizing compositions. The sizing composition described in the patent employs sodium silicate, an organic adhesive (e.g., glue) and a filler such as clay, casein, or starch in an aqueous solution. The composition is described as particularly adapted for use in sizing wood, paper and similar pulp boards and other articles consisting largely of cellulose or other fibrous or absorbent materials because the sodium silicate causes swelling of the fibers and allows them to be penetrated by the filler, thereby preventing the migration of moisture and organic liquids (e.g., paint) into the cellulosic material.
The use of sodium silicate in aqueous solutions to make water resistant compositions is also disclosed in U.S. Pat. No. 1,949,914. Modified aqueous sodium silicate solutions are described in the patent as containing complex amine compounds which facilitate the production of water resistant films.
In U.S. Pat. No. 1,466,241, a floor covering material is disclosed which consists of a mat covered with a mixture of powdered soya bean or the like albuminous substances, ammonia water, fibers as binding material, and pigment. The patent includes an example wherein sodium silicate is employed to solidify the albuminous substances which have been acted upon and dissolved by the ammonia. A coating is thereby obtained which is described as water proof and almost fireproof.
A method is disclosed in U.S. Pat. No. 2,485,287 for co-precipitating plastic materials and compounding ingredients in aqueous media. The method illustrates the difficulty encountered when one attempts to combine such materials. It requires the association of a coagulable aqueous dispersion of an organic plastic material, such as a natural or synthetic rubber or resin latex, with an aqueous solution of a water soluble reagent which is one component from which the compounding ingredient may be produced by chemical reaction, and with an aqueous solution of a second water soluble reagent reactive with the first reagent to form the compounding ingredient in a manner such that the various reactants remain in substantially distinct layers or moving streams while permitting diffusional intermingling of the separate reactants. A reaction of the water soluble chemical reagents is thereby effected to form the insoluble compounding ingredient in particulate form with simultaneous coagulation of the aqueous dispersion. An aqueous slurry is formed comprising the insoluble compounding ingredient enclosed or enmeshed in the plastic material. The plastic material is said to surround and enclose extremely small particles of insoluble compounding ingredient. An embodiment exemplified in the patent is a method of making a latex having water glass incorporated therein.
U.S. Pat. No. 4,510,201 describes polyvinyl chloride resin compositions combined with a cellular filler which reduces the density of the resin. A cellular filler is incorporated by dry blending polyvinyl chloride resin, a plasticizer, a stabilizer and the cellular filler, in a manner which does not destroy the cellular filler, to make a free flowing powder. Several inorganic cellular fillers are described as suitable, including sodium silicate. The patent also describes polyvinyl chloride sheet products containing cellular fillers which can be used in floor coverings to make them light, superior in flexibility and bending strength, dimensional stability, water resistance and improved adhesiveness.
None of the foregoing references resolve the need for a barrier layer which can be incorporated into a floor or wall covering material to inhibit the migration of organic stainants.